Agricultural round balers have been used for several decades to collect and bind crop material so as to facilitate the storage of crop material for later use. Generally, a mower or mower-conditioner cuts the crop and arranges it in a windrow for drying. Later, an agricultural tractor pulls a baler over the windrow to collect the crop material. The baler's windrow pickup gathers the cut and windrowed crop and lifts it into the baling chamber. The baling chamber consists of a pair of opposing sidewalls with a series of belts that rotate and compress the crop material into a cylindrically shaped bale. When the bale has achieved a desired size and density, the operator wraps the bale to ensure that the cylindrical and compact nature of the bale is maintained. There are many wrapping materials and methods of wrapping the bale depending on a variety of factors. After the bale is bound or wrapped, it is ejected from the baler for later pickup by the farmer.
Generally, round balers are pulled by an agricultural tractor and receive rotational power from the tractor's power-take-off shaft positioned at the rear of the tractor. The energy is transmitted to a gearbox positioned on the baler. Some balers also use a hydraulic motor and pump arrangement to provide energy to the various baler elements such as the various rollers and belts. As previously mentioned, balers often use net, twine, stretch film, plastic film, or other wrapping materials to wrap, and thereby confine and protect, bales of forage immediately after bale formation while the bales are still within the baler. In particular, conventional balers typically incorporate rolls of wrapping material rotatably supported by a wrapping material roll. An automated wrapping assembly feeds the wrapping material into the baling chamber where it is unwound from the roll to be wrapped around the exterior portion of the bale as the bale rotates in the baling chamber. The flow of wrapping material into the baling chamber is controlled by the rotation of the bale in the baling chamber, and the tension in the wrapping material is controlled by a brake device supplying an opposing drag force to the wrapping material roll.
The tension in the wrapping material is very important when wrapping the bale. For example, if the tension is too high, the wrapping material may not attach to the bale when entering the baling chamber. Or, once attached, it may tear and/or recoil from the baling chamber. If the tension is too low, the wrapping material will not spread properly along the length of the bale in a tight wrap. Insufficient tension during severing may leave a jagged edge or stringers at the end of the wrapping material that may catch on equipment, or the like, and cause the bale to unwrap. Accordingly, precise control over the tension in the wrapping material is desirable.
A brake device supplying an opposing drag force to the wrapping material roll provides the tension in the wrapping material when wrapping a bale. At the beginning of the wrapping process, little or no braking force is required to allow the wrapping material roll to begin rotation and feed wrapping material to the bale. As the wrapping material enters the baling chamber and catches on the bale, an increased braking force is required to increase tension so the wrapping material will spread along the entire bale while the wrapping. Increasing the tension too quickly or by too much may cause the wrapping material to tear and/or recoil from the baling chamber. Once the bale is wrapped, a braking force is required to create tension in the wrapping material to facilitate a clean cut.
The required increase in tension in the wrapping material remains consistent from bale to bale, however, the braking force required to achieve a particular tension may vary based on wrapping material characteristics. For example, each wrapping material, such as twine, black net, white net, stretch film, plastic film, and the like, requires a different braking force to provide a similar amount of tension in the wrapping material. Also, as wrapping material is used, the braking force required to produce a particular tension in the wrapping material decreases as the amount of wrapping material on the roll decreases.
Present systems typically use mechanical brake mechanisms to apply a level of braking force in an “on” or “off” manner. These mechanisms are usually manually adjusted for each type of wrapping material. They also must be adjusted for the diameter of the roll of wrapping material. The proper adjustment may be difficult to determine without trial and error, resulting in possible tearing, recoil, poor spread, poor cut, or bunching of the wrapping material. These mechanisms are also typically complicated to adjust resulting in frustration and lost time for the operator.
Thus, what is sought is a bale wrapping apparatus and method including a computer controlled brake device that automatically and precisely controls the tension exerted on the wrapping material in a predetermined or controlled manner for placing the wrapping material around a round bale which overcomes at least one of the problems, shortcomings or disadvantages set forth above.